Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

582
FXUS63 KLOT 300001
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
701 PM CDT Wed Apr 29 2026

.KEY MESSAGES...

- Cooler daytime temperatures, afternoon showers, and chillier
  nights through the end of the week

- Patchy frost possible tonight and Friday morning, with the
  potential for widespread frost Saturday morning.

- Warmer and wetter conditions potentially late in the weekend.

&&

.DISCUSSION...
Issued at 149 PM CDT Wed Apr 29 2026

A 500 mb long wave trough over the upper Midwest will become a
closed low overnight over southern Ontario and gradually move
east through Saturday. Embedded shortwaves within the upper
level troughing will provide occasional opportunities for
showers this afternoon through Friday. Cloud cover this
afternoon has limited daytime heating, but with an area of
convergence near the lake due to the onshore winds, spotty
showers are possible through the early evening, but will diminish
quickly after sunset. Temperatures will fall into the 30s
overnight. If winds decouple enough along with the decreased
cloud cover tonight, patchy frost is possible tomorrow morning.

The wave is expected descend southward within the upper level
pattern on Thursday afternoon. While the entire forecast area
has a slight chance of a shower tomorrow, hi-res models are
suggesting a slightly more southerly track to the wave leaning
higher chances south of I- 80 tomorrow. Persistent northerly
winds will continue to filter in cooler air to the region. As
skies clear out again and winds diminish, there is another
chance for patchy front Friday morning.

Guidance suggests yet another wave to descend down through the
pattern on Friday providing another chance for showers Friday
afternoon. The coldest air is expected to arrive overnight for
probably the best chance for widespread frost to develop
Saturday morning.

Weak ridging moving in from the west should finally break the
string of shower chances and allow for a drier weekend. As winds
turn to the southwest, it should filter in a (relatively)
warmer air mass. It will not be a heat wave, but should help
bring temperatures back up a little and approach the low 60s by
Sunday. However, the next trough is expected to descend out of
Canada Sunday providing the next chance for rain. There is still
model disagreement on timing and location. With better forcing
and instability, there could be some thunder embedded with these
showers, but most guidance has the better instability to the
south. Warmer temperatures will stick around early next week
with another storm system potentially midweek.

DK

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 701 PM CDT Wed Apr 29 2026

Aviation forecast concerns for the 00Z TAFs:

- Few lingering spotty SHRA early this evening, then another
  chance of SHRA Thursday afternoon/evening. Patchy MVFR cigs
  possible in precip.

- NNE winds at ORD/MDW/GYY become NW/WNW overnight into
  Thursday, then E-ENE again Thursday afternoon.

Shower coverage has decreased markedly since mid-afternoon,
though a few spotty showers will remain possible across the
terminals early this evening as a mid-level trough moves across
the area. Have maintained a VCSH mention for this, though
coverage may be on the light side. Patchy MVFR cigs were noted
over/near Lake Michigan and into southeast WI at issuance time,
though are mainly affecting GYY with ORD/MDW just west/south of
more solid MVFR coverage. ORD/MDW are expected to remain
primarily VFR with a gradual decrease in overall cloud cover
overnight.

Surface winds will shift northwest at ORD/MDW/GYY later this
evening and remain so through Thursday morning. Another lake-
assisted wind shift to east-northeast is expected early-mid
Thursday afternoon however. This will about coincide with
increasing rain shower chances which will develop from west-east
across the terminals in association with another approaching
mid-level disturbance. Highest coverage of showers looks to be
from mid-afternoon into early Thursday evening, then decreasing
beyond that time. Patchy MVFR ceilings will be possible mainly
in precipitation during that time.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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